Authors:

Jian Wei(Northwestern University)

Paul Cadden-Zimansky(Northwestern University)

Venkat Chandrasekhar(Northwestern University)

We measure the magnetoresistance of a dc SNS SQUID in the form
of a
mesoscopic normal-metal loop in contact with two superconducting
electrodes. Below the transition temperature of the
superconducting
leads, large $h/2e$ periodic magnetoresistance oscillations can
be
observed when the normal sections of the SNS junctions enter a
proximity
regime induced by the superconducting electrodes. As the
temperature is
lowered, the entire device becomes superconducting. In this
regime,
sharp switching from the zero-resistance state to a
finite-resistance
state is seen at half-integer flux quanta. With the application
of a dc
bias current at even lower temperatures, periodic switching from
the
superconducting state to the fully normal state can be produced
with the
external field. The observation of periodic flux-driven
transitions in
this device suggests that beyond the current SQUID theory for
SIS
junctions the development of SQUID theory for SNS junctions that
incorporates the kinetic energy of the coherent electrons in the
junctions is needed.

*This work was funded by the NSF through grant DMR-0604601.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2008.MAR.Y10.4